From the Leads screen you are able to search / filter for leads using the different filter options that are available to you.  For example; you can filter for leads based sold status, by Campaign or Country, by date or by specific Buyer or Delivery.  Furthermore, you can search for leads based on Standard or Custom fields criteria.  For example, you may wish to search for all leads that were sold where the lead was in a specific town and the customer stated that they are a homeowner.

By default, no filters will be applied and the leads that will appear when you first enter this screen will display leads from the current day for both API and Import submissions. However, there are several filter options that can be used to narrow down your search.

Campaigns
You can select specific Campaigns to search by here, whilst also searching for Campaigns using their relative Campaign ID (useful if you run 100s of Campaigns).  Note, when you select a Campaign you are able to then search for leads using any field against that Campaign (both Standard and Custom fields).  This extended search on Custom fields is only available when 1 Campaign is selected.

Date & Time
Specify the date-range for your lead search (leads older than 60 days will not show Delivery data)

Fields
By default, you can search by several Standard fields and use certain filter types to sieve through the values like Email does not contain @gmail (whilst also using Paste Values under Keyword). Please note that you can search by Custom fields if only ONE Campaign has been selected.  You can use the "Add Filter" option if you want to filter by multiple field values.  This uses the AND logic when entering in values.

Country
This enables you to search for leads that are linked to a specific Campaign Country (not the country necessarily of of Lead).

Delivery - you can select specific Deliveries to search by here, whilst also searching for Deliveries using their relative Delivery ID (useful if you run 100s of Deliveries)

Suppliers
Search for leads submitted by selected Suppliers.

Buyers
You can select specific Buyers to search by here, whilst also searching for Buyers using their relative Buyer ID (useful if you have 100s of Buyers).  This is commonly used if you want to see leads that have been assigned to a Buyer.

Lead Activity
This enables you to filter by leads that have been resubmitted from system rejections, manually processed by a user, test leads or where leads have either Buyer or internal feedback.  From the dropdown you will see the options available.  

Method
Search by both or either API/Imported leads.

Sold status
Only show leads that are Sold, Unsold, Returned, Multi-Sold or Single-Sold.  For many clients, some leads are sold exclusively or non-exclusively so this will enable you to have better visibility on that.

Delivery Status
For none buyer deliveries only, using the below options
Full - The lead has been delivered to all of the connected deliveries
Partial - The lead has been sent to some of the linked delivery
Fail - The lead has NOT delivered to the linked deliveries
Blank - No deliveries have been linked to this lead for processing

Columns 
Only show the specified columns selected here (subjected to only Standard Fields).  When you select the fields that you want to see on the leads table, this is custom to you.  Other users will not see what you see.  Clients that use this typically want to see at a glance specific lead data at a glance on screen such as Name, Email, Phone etc.